The present technology relates to an image signal processing apparatus, a method for processing an image signal, an imaging apparatus, and a method for displaying an image. More specifically, the present technology relates to an image signal processing apparatus and the like which process an image signal having a high resolution to obtain an image signal having a low resolution and being to be displayed.
In general, a camera (imaging apparatus) includes a viewfinder (display device) for checking, in real time, the composition or focus of an image being captured. Preferably, the viewfinder can faithfully reproduce thereon the view angle or resolution of the image being captured. However, many 4K-resolution imaging apparatuses (4K cameras), for example, use a viewfinder having a resolution lower than that of images to be captured, such as a high-definition (HD) resolution, so as to make it easy to move or place the imaging apparatuses.
The function of highlighting edge information extracted from a viewfinder image (edge display function) has been known as a marker for helping manually achieve focus on the viewfinder (for example, see Japanese Unexamined Patent Application Publication No. 2007-060328). Since the change (edge) in signal level is abrupt in the portion in focus, this function allows the user to check the degree of focus by looking at the highlighted edge.